Abstract:

【Aim】 This study aims to investigate the correlation of the full-length transcripts in Ascosphaera apis mycelium (Aam) and spore (Aas) with the mycelium growth, spore germination and sexual reproduction. 【Methods】 The congruent information about the full-length transcripts and known transcripts was obtained by aligning the clean reads generated from the previously gained Nanopore long-read sequencing data of Aam and Aas to the known transcripts annotated in the reference genome of A. apis. Bioinformatics methods were used to analyze the differential expression pattern, functional annotation and structural characteristics of the full-length transcripts in Aam and Aas. 【Results】There were 19 966 full-length transcripts in both Aam and Aas. The specific full-length transcripts of Aam and Aas were 1 273 and 2 856, respectively. In the Aas vs Aam comparison group, 3 230 differentially expressed transcripts (DETs) including 3 072 up-regulated and 158 down-regulated transcripts were identified. These DETs involve such GO items as metabolic process, cell, catalytic activity, etc. KEGG pathway annotation analysis demonstrated that these DETs are involved in pathways including endocytosis, MAPK signaling pathway, glycolysis/gluconeogenesis, carbon metabolism, and amino acid biosynthesis. Further investigation indicated that the splicing isoforms of some full-length transcripts had different expression levels and structure in Aam and Aas. 【Conclusion】 In this study it was discovered that the expression levels and structure of transcripts in A. apis vary in the two stages of mycelium and spore. These results provide a theoretical and data foundation for deeply investigating the molecular function of various splicing isoforms involved in the mycelium growth, spore germination and sexual reproduction of A. apis.

Key words: Ascosphaera apis, mycelium, spore, differentially expressed transcript, full-length transcript, third-generation sequencing